Whip 4 egg in a stand mixer on high speed for about 1 minute, then add 1.5 cups powdered sugar (or 1 cup of granulated sugar) in thirds while continuing to whip.

Preheat oven to 350F with the rack in the middle. Line a 8 inch round cake pan (at least 2 inches tall) lined with foil and sprayed with non stick spray. Alternatively you can brush room temperature butter on the inside of the pan, then dust it with flour, knocking out the excess to make the surface non-stick.

Fasten the wet baking strips around the baking pan for an evenly risen cake (optional).

Combine the melted butter and hot water in a cup and whisk together to mix.

Whip the eggs and sugar for about 15-20 minutes or until the batter ribbon falling off the whisk doesn't disappear for about 2-3 seconds. You want to make sure the eggs are properly whipped before continuing with the next steps for successful rise of the cake in the oven.

Add 1 Tbsp of vanilla extract.

Now add the flour into the whipped eggs in halves, carefully folding with a spatula forming the number 8 with each stroke. Do not overfold or the cake will be tough. Just fold enough to incorporate the flour.

Add the melted butter mixture into the batter and carefully fold with a spatula until no streaks of liquid are seen.

Bake the cake for about 30 minutes on the middle rack of preheated to 350F oven. Check the cake with a toothpick/skewer by inserting it in the middle. If it comes out clean with no crumbs on it, the cake is ready to be removed from the oven. Remove it to a cooling rack and allow to sit undisturbed for 5-10 minutes. Then invert it onto a cooling rack and remove the foil. Allow to completely cool before using.

For best results leave the cake on the counter for 6-8 hours before using in a cake. This will reduce the amount of crumbing when you go ahead to split the cake layer in two horizontally.